Apparatus for making insulated electrical conductors



Jan. 24, 1939. E. D. BENT 2,144,868

APPARATUS FOR MAKING INSULATED ELECTRICAL CONDUCTORS Filed Feb. 21, 1935INVENTOR E. D. BENT R MM ATTORNEY Patented Jan. 24, 1939 PATENT OFFICE.

msaa'ros roa MAKING msum'ran ELECTRICAL connuo'roas m b. Bent, Montreal,Quebec, Canada, assignor to Western Electric Company, Incorpor a te l,New York, N. Y., a corporation of New Application February 21, 1935,Serial No. 7,487 2 Claims. (01. 173-244) This invention relates toapparatus for making insulated electrical conductors provided withinsulation which is both electrically and thermally insulating and moreparticularly to an apparatus for compacting such insulation materialupon conductor strands.

Asbestos fibresglave been used to make thermally and electricallyinsulating sheathing for conductor strands in the form of yarns andother strands and have often given difllculty in the handling of theasbestos during application and in the varying quality and resistance ofthe coating after being applied because of the weak interlocking powerof asbestos fibres and the low tensile strength of the fibres inthemselves.

One object .of the present invention is to "pgvide an improved apparatusfor making an as tos insulated conductovin which the asbestos layer ofthe coating is of relatively uniform character throughout and has acomparatively compact, smooth and dense surface,

' With the above and other objects in view, one embodiment of theinvention may be in an apparatus for making insulated conductors whichincludes means to tease up and polish down in one operation the exteriorsurface of an outer sheath of fibrous material on an electricalconductor, such means comprising a polishing member having a roughenedportionand a smooth portion to be applied to the sheathsuccessively.Other objects and features of the invention will appear from thefollowing detailed descripdevice, and

Fig. 3 is a detached face view of one of the blades thereof. In theembodiment of the invention herein disclosed there is presented anapparatus for teasing up and polishing down the exterior surface of anouter sheath of fibrous material on a conductor strand- Such a sheathmay be of any fibrous material applied in any suitable manner, but theinvention is particularly applicable to a specific type of asbestossheathed wire. Fig. 1 shows a compound sheathing strand 2| in which arelatively bulb and loosely twisted roving or "strand 2! of intertwistedasbestos fibres has a relatively slender and tightly twisted som orthread 2| of spun cotton or like,- twisted about [the asbestos. Strandssuch as may be served or braided on a conductor strand to a bothelectrically and thermally insulating sheath. A conductor having such asheath may often be materially improved in appearance and quality byhaving its outer surface smoothed, evened and compacted by teasing upand polishing down the fibres of its outer surface.

A suitable device for doing this and embodying the present invention isdisclosed in Figs. 2 and 3.

As there shown, a block 5| having an axial perforation or bore Ii ismounted by a base 55 and struts or legs 52 on a rotary support 53supported and driven in any approved fashion not shown and provided withanaxial aperture 54, the strand being operated on passing axiallythrough the aperture I4 and the bore ii. A pair of complementary,coacting polisher blades 561s positioned loosely in the bore, eachsupported on a pair of pins 51, 5'1 rigidly mounted in the blade andslidabie in corresponding transverse bores in the block 52. The twoblades are pressed yieldingly together by two compression springs 58,58, each bearing at one and against the rear face of one of the bladesand at the other against a stop 59 which is adjustable as shown by meansof a thumb screw 60 mounted in the block 52.

Guide pins SI for the spring may also be provided. The inner or workingface of eachblade has a longitudinal groove 82 transverselyarcuatelycurved the bottom of which bears against a strand beingpolished. That portion of each working face of the blades which firstcomes into contact with the strand is knurled or serratelygrooved orotherwise roughened, as by sand blasting, as shown at 63 in Fig. 3. Ithas been found that a fairly sharp cross knurling as shown issatisfactorily effective to tease up and comb out the surface of anasbestos sheathed wire such as described above to prepare it for beingsmoothed down by the polishing action of the smooth portions of theblades. If this roughening and teasing is not performed, a. satisfactoryresult may be obtained for some purposes where uniformity of diameteralong the strand is not important, but where as in many cases it isnecessary to achieve relatively great uniformity, this teasing rendersit possible as the rou'ghening breaks up minor knotsand tangles in theasbestosfibresand lays the fibres on the surface in combedalignmentready for the actual compacting and polishing by the smoothportions.

p The embodiments of the invention herein disclosed are illustrativeonly and may be widely and variously modified and departed from withoutdeparting from the scope and spirit of the invention as pointed out inand limited only by the appended claims.

What is claimed is:

1. In an apparatus for making an insulated electrical conductor having asheath of asbestos fibre, means to tease the surface of the sheath andmeans to compact and polish the teased surface comprising a polishingmember having a roughened portion and a smooth portion to be applied tothe sheath successively.

2. In an apparatus for making an insulated electrical conductor having asheath of asbestos fibre, means to tease the surface of the sheath andmeans to compact and polish the teased surface comprising a pair ofcoacting polishing members each having a roughened portion and smoothportion to be applied to the sheath successively.

EDGAR D. BENT.

